Mechanical seals have been used to provide a fluid seal between a rotatable shaft and a fluid containing chamber. As such, mechanical seals have application in pumps where the drive shaft of an externally mounted pump motor extends through a pump casing to drive a pump impeller. In such an application, the mechanical seal is typically situated where the rotatable shaft enters or leaves the casing and is fitted to the casing and the rotatable shaft to provide a seal between those components.
Such mechanical seals generally comprise some components which rotate with the shaft (or other rotatable portion of the equipment to which it is fitted) and those components which are fitted to the stationary parts of the equipment. At the interface between these rotary and stationary components are contacting sealing faces; one which rotates and the other which is stationary. These sealing faces are in opposed relation and arranged to be urged into contact to form a fluid seal therebetween.
In the past, problems have been encountered in using mechanical seals in some pumping applications, particularly in mining slurry pumps because of the harsh environment created in the pumps by the slurry, the high loading induced on the pump components during start up and operation, and the need for continual operation of the pumps over extended periods. Accordingly, there is an ongoing need to improve the design of the mechanical seal to improve its suitability in pumping applications.